Fixation augmentation device and related techniques

ABSTRACT

A Fixation Augmentation Device (FAD) is presented. The FAD includes a tubular body or sleeve ( 902 ) having a collar ( 904 ) disposed on a first end thereof. The sleeve is provided having an outside diameter selected such that the sleeve fits into a hole drilled in a bone. The collar at the first or proximal end of the sleeve prevents advancement of the FAD into the hole with screw insertion. Flanges ( 908 ) are provided at the distal portion of the sleeve to provide interference fixation of the FAD to the bone, thereby allowing the screw and FAD to obtain purchase where a screw alone would have failed or otherwise have inadequate fixation. The FAD is also designed to collapse as it is withdrawn from the drill hole in the event of removal of the device is desired.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of PCT Application No.PCT/US2004/014640 filed on May 10, 2004 which claims the benefit ofprovisional patent application Ser. No. 60/468,829 filed May 8, 2003,the disclosure of which is incorporated herein by reference and thisapplication is a continuation-in-part (CIP) of patent application Ser.No. 10/246,304 filed on Sep. 18, 2002, which claims the benefit ofprovisional patent application Ser. Nos. 60/323,347 filed on Sep. 18,2001, 60/347,212 filed on Jan. 10, 2002, and 60/374,534 filed on Apr.22, 2002 the disclosures of which are each incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

FIELD OF THE INVENTION

The present invention relates generally to surgical fasteners. Moreparticularly, the present invention relates to a mounting or anchoringdevice for use with a screw or bone being fastened to a bone or otherbody structure.

BACKGROUND OF THE INVENTION

As is known in the art, fasteners such as screws or pins are commonlyused to secure or mate fractured bone sections. For example, a bonefracture can be held together during the healing process by means of afastener such as a surgical screw. Such screws and the manner in whichthe screws are selected for use are known.

The process of inserting the screw involves first properly aligning thebone regions to be secured by the screw. A hole is then drilled throughthe bone regions. After the hole is drilled, the hole is tapped. Thediameter of the screw to use, the size of the hole to drill, and thesize of the tap are selected in accordance with a variety of well-knownfactors including but not limited to the size of the bone as isgenerally known by those of ordinary skill in the art.

One problem that arises, however, is that as a screw is being insertedinto the hole in the bone, the screw hole may become stripped and thescrew no longer obtains adequate purchase in the bone. A screw havinginadequate purchase is sometimes referred to as a “spinner.” Reasons forthis failure of fixation include poor bone quality, over-tightening ofthe screw and an error in the drilling or tapping of the screw hole(e.g. the tap itself cuts a new hole because the tap does not enter thedrilled hole at the proper angle, the drill does not produce a straighthole, etc. . . . ). Other problems can also occur. For example, whilethe hole is being drilled, the fracture may shift which results in theexisting hole being in a sub-optimal position.

One technique for addressing such a problems is to inject a bone cement(e.g. methylmethacrylate) into the screw hole and re-insert the screwwhile the bone cement hardens. This is a cumbersome and time-consumingprocess and also runs the risk of having the bone cement travel into thefracture site and impeding bony union. As a result of these and otherrisks, this technique is seldom utilized.

Another technique, which is more frequently utilized than the bonecement technique, is to attempt to drill another hole in a new position.However, this is not always possible due to a variety of factorsincluding but not limited to the type and location of the bone fracturebeing repaired as well as the condition (e.g. quality) of the bone beingrepaired. A new drill hole may now create too large a drill hole or adrill hole with too thin a wall adjacent to the previous hole and againcompromise or eliminate effective screw purchase. It is sometimesnecessary to simply accept less than optimal fixation, or in some caseseven substandard fixation, and possibly alter the post-operativerehabilitation plan. This may entail delaying weight-bearing or earlymotion and possibly compromising the patient's outcome.

In some cases, bone plates are used to obtain fixation and are commonlysecured to the bone by screws. The use of bone plates can improvestability of the fractured bone gained by applying compression acrossthe fracture site. Use of bone plates, however, can also make it moredifficult to deal with spinners since the holes drilled in the bonesmust also match the locations of pre-drilled holes in the bone plates.

Another problem that arises is that osteoporotic bone or bone withabnormally thinned cortices due to failed fixation or previous infectionmay not allow lasting screw purchase in the bone. Thus, a surgical screwmay first appear to have adequate purchase but due to bone or otherconditions, the screw fails to maintain adequate screw purchase in thebone over a requisite period of time. Once the screw loosens in thebone, stability of the fractured bone gained by applying compressionacross the fracture site is quickly lost. A number of techniques forsecuring screws in a bone plate are described in U.S. Pat. Nos.5,976,141 and 4,484,570.

SUMMARY OF THE INVENTION

In accordance with the present invention, a Fixation Augmentation Device(FAD) includes a tubular body or sleeve having a collar disposed on afirst end thereof. The sleeve is provided having an outside diameterselected such that the sleeve fits into a hole drilled in a bone. Thecollar at the first or proximal end of the sleeve prevents advancementof the FAD into the hole with screw insertion. With this particulararrangement, a device that allows a surgeon to quickly remove a“spinner” screw and reinsert the screw in a manner such that a screwwhich obtains adequate purchase is provided. Furthermore by utilizingthe FAD the originally selected angle of the screw relative to thefracture is maintained. The FAD improves screw purchase by effectivelyrestoring the appropriate sized hole for screw purchase thereby givingpress fit interference fixation along the inner walls of the drill hole.The outer walls of the FAD can be ribbed, threaded, fretted or otherwisetextured to enhance this fixation. In addition, the shape of the outerwall of the interference portion allows the FAD to hook over the bonecortices to further enhance fixation. The FAD thus takes advantage ofthe tubular aspect of the bone in order to secure fixation within thebone and outside the bone. The FAD is designed to allow the screw toobtain secure fixation to the bone in the situations where a screw hasinadequate purchase. The FAD is a relatively simple device which isrelatively easy and inexpensive to manufacture and to use. Furthermore,the FAD adds no significant operative time to install.

In one embodiment, the FAD can be used with a bone plate. In such anembodiment, the collar portion of the FAD is provided having a size andshape which allows the sleeve portion of the FAD to be inserted into ahole in a bone through a bone plate. Thus, when the FAD is used inconjunction with a bone plate, the sleeve portion of the FAD fitsthrough an opening in the bone plate and is inserted into a hole whichhas been drilled in a bone while the collar portion of the FAD fitsthrough the opening in the bone plate but does not fit within the holein the bone. The collar portion of the FAD can be provided having ashape which allows insertion of the FAD through the opening in the platebut which prevents rotation of the FAD during screw insertion. Forexample, in the case where the opening in the bone plate is providedhaving a round shape, the collar portion of the FAD can be providedhaving an oval shape. In this case, the edges of the collar would makeinterfering contact with the walls of the plate which define the hole tothereby prevent rotation of the FAD. This would not be accomplished witha round collar. Small fins beneath the collar can also help toaccomplish this task. The tapered fins are directed radially justbeneath the collar portion and cut into the proximal cortical edge. Whena rotational force is applied during screw insertion these radial finsin the FAD provide a de-rotation mechanism and facilitate the passage ofthe screw.

In one embodiment, the sleeve portion of the FAD is tapered and thewalls of the sleeve are provided having a slot provided therein. Theslots extend through the entire thickness of the sleeve. The slot may beincorporated on only one sidewall of the device, or may extend throughthe device, thus being incorporated into the sidewall in two places. Asa screw is inserted into the FAD, the slot in the sleeve portion of theFAD allows the sleeve portion of the FAD to expand thus pressing thewalls of the sleeve into the bone on the inner walls of the drill hole.

In another embodiment, the FAD includes a flange at the distal end ofthe sleeve (i.e. at the opposite end of the sleeve from the collar). Thesleeve portion of the FAD is tapered and the walls have a slot providedtherein. The slots extend through the entire thickness of the sleeve.The flange portion at the distal end of the FAD hooks over the far sideof the distal cortex as the screw is seated. This is accomplished by theexpansion of the sleeve due to the screw entering the sleeve. Theexpansion can be enhanced by filling a portion of the distal end of eachinner surface of the sleeve such the outer surface of the distal end ofthe screw pushes against the filled inner surface at the distal end ofthe sleeve. As the screw passes from the hollow portion of the sleeveinto the filled distal end portion of the sleeve it abuts the solidinner wall which causes further expansion of the distal end and alsoprevents the flange from collapsing when pullout stress is applied. Thisapproach further increases pullout strength of the FAD.

In accordance with a further aspect of the present invention, a bonefixation augmentation device, for use in a bone having a hole providedtherein, includes a first collar portion adapted to mate to a firstsurface of a bone, an interference region projecting from the firstcollar portion and having a length and a width adapted to produce aninterference fit between a fastener inserted in the hole and a hole wallsurface. With this particular arrangement, a device for improving thepurchase of a screw is provided. In one embodiment, the first collarregion is disposed at a first end of the interference region and isdisposed on the surface of the bone at a first end of the hole to securethe interference region in a desired location within the hole. A second,opposite end of the interference region has a second collar portioncoupled thereto. The second collar portion is adapted to mate to thesurface of the bone at a second, opposite end of the hole. The secondcollar region secures the interference region of the FAD in the hole andincreases pullout strength of the FAD. In another embodiment, the FADincludes an anti-rotation structure which prevents the FAD from rotatingwithin the hole in the bone. The anti-rotation structure can be providedas part of the first or second collars or as part of the interferenceregion.

In still another embodiment, the interference region is provided havingone or more slots therein to allow expansion of wall which comprise theinterference region in response to a screw passing through theinterference region.

In still another embodiment, the interference region is provided havingridges or teeth on an outer surface thereof and one or more slotstherein. The slot(s) allow expansion of walls which comprise theinterference region in response to a screw passing through theinterference region and the ridges help secure the FAD within the bonehole.

In still another embodiment, the interference region is provided havingthreads on an internal surface thereof. The threads mate with screws tobe inserted within the FAD.

In still another embodiment, the interference region includes wings in aportion thereof which expand in response to a screw passing through theinterference region and which secure the FAD within the bone hole.

In still another embodiment, the interference region includes wings inan end portion thereof which expand in response to a screw passingthrough the interference region such that when the wings are deployed,the wings engage an outer surface of the bone and increase the pullforce required to remove the FAD from the bone hole.

In yet another embodiment, the interference region is provided havingportions thereof such that the interference region corresponds to aspring-like or clip-like structure. The interference region can also beprovided having threads which mate with screws to be inserted within theFAD.

In accordance with the present invention, a Fixation Augmentation Device(FAD) includes a tubular body or sleeve having a collar disposed on afirst (proximal) end and a plurality of expandable flanges disposedabout a second (distal) end. The FAD allows a screw to obtain securefixation to a bone in the situations where a screw or other securementdevice may have inadequate purchase. The FAD adds no significantoperative time to install.

In accordance with a further aspect of the present invention, a FixationAugmentation Device (FAD) includes a tubular body or sleeve having acollar disposed on a first end thereof. The sleeve is provided having anoutside diameter selected such that the sleeve fits into a hole drilledin a bone. The collar at the first or proximal end of the sleeveprevents advancement of the FAD into the hole with screw insertion. Thesleeve includes a thread for receiving a screw. The sleeve includes oneor more flanges extending a predetermined distance from a distal end ofthe sleeve. The portions of the sleeve defined by the slots are referredto as flanges. The flanges are displaceable at the point where theflange joins the sleeve. The flanges are displaced from a closedposition to an open position by insertion of the screw. In use the FAD(with the flanges in a closed position) is inserted into the holedrilled into the bone. Once the FAD has been positioned within the hole,a screw is inserted into the FAD. As the screw is inserted into thesleeve of the FAD, the screw displaces the flanges into an open positionthat provides an interference fixation of the FAD within the hole.

The FAD is designed to allow the screw to obtain secure fixation to thebone in the situations where a screw has inadequate purchase. The FAD isalso removable by removing the screw and pulling the FAD out of thehole. The flanges are collapsible back to the closed position therebyallowing the FAD to be readily removed. The FAD adds no significantoperative time to install.

In one embodiment, the FAD is used with a bone plate. In such anembodiment, the collar portion of the FAD is provided having a size andshape that allows the sleeve portion of the FAD to be inserted into ahole in a bone through a bone plate. Thus, when the FAD is used inconjunction with a bone plate, the sleeve portion of the FAD fitsthrough an opening in the bone plate and is inserted into a hole whichhas been drilled in a bone while the collar portion of the FAD fitsthrough the opening in the bone plate but does not fit within the holein the bone. The collar portion of the FAD can be provided having ashape which allows insertion of the FAD through the opening in the platebut which prevents rotation of the FAD during screw insertion. Forexample, in the case where the opening in the bone plate is providedhaving an oval shape, the collar portion of the FAD can be providedhaving an oval shape. In this case, the edges of the collar would makeinterfering contact with the walls of the plate that define the hole tothereby prevent rotation of the FAD. This would not be accomplished witha round collar.

In another embodiment, the FAD is again used with a bone plate however,this arrangement is different than the one described above. In thisembodiment, the FAD is inserted into the bone and the bone plate isplaced on top of the FAD. The hole in the bone plate is aligned with thehole of the FAD, and a screw is inserted through the hole in the boneplate and into the FAD to securely attach the bone plate to the FAD wilealso securely affixing the FAD within the hole in the bone.

In yet another embodiment, a locking plate is used in combination with aFAD. The locking plate features a tapered threaded hole which receives aFAD provided with external threads which mate with the threads of thehole. The FAD may be configured such that a fully inserted FAD has it'stop surface aligned with a top surface of the locking plate. In analternate embodiment the FAD may be configured such that a fullyinserted FAD has it's top surface recessed below the top surface of thelocking plate. In still another embodiment, the FAD could be configuredto a locking plate with a straight threaded hole as well as the taperedhole mentioned above.

In yet another embodiment the FAD is provided with an external threadfor securing the FAD within a bone plate and is further provided with aslot in the inner surface of the collar. The slot accepts a flat screwdriver blade and can be used to remove the FAD from a bone plate.

In still a further embodiment the FAD is integral with a bone plate. Thedevice could include multiple FAD portions, all integrated with the boneplate into a single device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A is a diagram of a first embodiment of a FAD;

FIG. 1B is a cross-sectional view of the FAD of FIG. 1A;

FIG. 1C is a top view of the FAD of FIG. 1A;

FIG. 2 is a diagram of a second embodiment of a FAD;

FIG. 3A is a diagram of a third embodiment of a FAD;

FIG. 3B is a side view of the FAD of FIG. 3A;

FIG. 4A is a side view of a fourth embodiment of a FAD;

FIG. 4B is a cross-sectional view of the FAD of FIG. 4A with a screwinserted therein;

FIG. 5 is a side view of a fifth embodiment of a FAD;

FIG. 6A is a side view of a sixth embodiment of a FAD;

FIG. 6B is a side view of the FAD of FIG. 6A with a screw insertedtherein;

FIG. 7A is a side view of a seventh embodiment of a FAD;

FIG. 7B is a side view of the FAD of FIG. 7A with a screw insertedtherein;

FIG. 8 is a diagram showing a tool used for insertion of a FAD into abone;

FIG. 9A is an isometric view of the FAD of the present invention in aclosed position;

FIG. 9B is an isometric view of the FAD of FIG. 9A in an open position;

FIG. 9C is a side view of the FAD of FIG. 9B;

FIG. 9D is a cross-sectional side view of the FAD of FIG. 9B takenacross lines 9D-9D of FIG. 9B;

FIG. 9E is a top view of the FAD of FIG. 9B;

FIG. 9F is a bottom view of the FAD of FIG. 9B;

FIG. 9G is an enlarged view of a portion of the FAD shown in FIG. 9Dtaken along lines 9G-9G;

FIG. 10 is a cross-sectional side view of a FAD having threads extendingthere through;

FIG. 11 is a side view of a third embodiment of a FAD;

FIG. 12A is a side view of a collar having a tapered upper surface;

FIG. 12B is a top view of the FAD of FIG. 12A;

FIG. 13A is an isometric view of a fourth embodiment of a FAD in aclosed position;

FIG. 13B is an isometric view of the FAD of FIG. 13A in an openposition;

FIG. 13C is a top view of the FAD of FIG. 13B;

FIG. 13D is a cross-sectional side view of the FAD of FIG. 13B takenalong lines 13D-13D in FIG. 13C;

FIG. 14A is a isometric view of a further embodiment of a FAD having acollar slot;

FIG. 14B is an isometric view of a second embodiment of a FAD having acollar slot;

FIG. 14C is a top view of the FAD of FIG. 14B;

FIG. 14D is a side view of a third embodiment of a FAD having a collarslot;

FIG. 15 is an exploded view of the FAD being used with a bone plate;

FIG. 16 is an exploded view of a second arrangement of a FAD used with abone plate;

FIG. 17A is a cross-sectional side view of a locking plate and FAD;

FIG. 17B is a cross-sectional side view of the locking plate andrecessed FAD; and

FIG. 18 is side view of a FAD integrated with a bone plate.

FIGS. 19A and 19B are isometric views of a FAD having a release-cammechanism;

FIG. 19C is a cross-sectional side view of the FAD of FIGS. 19A and 19B;

FIG. 19D is a cross-sectional view taken across lines 19D-19D of FIG.19C;

FIG. 19E is a cross-sectional view taken across lines 19E-19E of FIG.19C;

FIG. 19F is a side view of the expanded portion of the FAD of FIG. 19C;

FIG. 19G is a side view of the tab portion of the FAD of FIG. 19C; and

FIG. 20 is a cross-sectional view of a FAD inserted in a bone.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, a Fixation Augmentation Device(FAD) includes a tubular body or sleeve having a collar disposed on afirst end thereof. The sleeve is provided having an outside diameterselected such that the sleeve fits into a hole drilled in a bone. Thecollar at the first or proximal end of the sleeve prevents advancementof the FAD into the hole with screw insertion. With this particulararrangement, a device that allows a surgeon to quickly remove a“spinner” screw and reinsert the screw in a manner such that a screwwhich obtains adequate purchase is provided.

The FAD allows a surgeon to quickly remove a “spinner” screw andreinsert the screw in a manner such that the screw obtains adequatepurchase is provided. Furthermore by utilizing the FAD the originallyselected angle of the screw relative to the fracture is maintained. TheFAD improves screw purchase by effectively restoring the appropriatesized hole for screw purchase thereby giving press fit interferencefixation along the inner walls of the drill hole. The shape of the wallsof the FAD further enhance fixation by hooking over one or more corticesof the bones after screw insertion. The FAD is designed to allow thescrew to obtain secure fixation to the bone in the situations where ascrew has inadequate purchase. The FAD is a relatively simple devicewhich is relatively easy and inexpensive to manufacture and to use.Furthermore, the FAD adds no significant operative time to install.

Referring now to FIGS. 1A-1C, a bone Fixation Augmentation Device (FAD)10 includes a tubular body or sleeve 10 corresponding to an interferenceregion. The sleeve 10 has a collar 20 disposed on a first end thereof.The sleeve 10 is provided having an outside diameter selected such thatthe sleeve fits into a hole drilled in a bone. The collar at the firstor proximal end of the sleeve prevents advancement of the FAD into thehole with screw insertion. A first interference region 40 is provided aspart of the sleeve 20. Upon insertion of a screw 70 into core 30 of thesleeve 20, the first interference region (flange) 40 expands into thehollow part 90 of the bone, providing secure fixation of the FAD to theinner cortex portions 80 of the bone. The angled sidewalls of theinterference region and the flange are provided such that the FAD may beremoved from the hole in the bone if desired. Removal of the screwallows the flange sidewalls and interference region sidewalls tocollapse such that the FAD can be removed. A flange 50 is disposed on asecond end of the sleeve 20. Upon insertion of screw 70 into core 30 ofthe sleeve 20, the flange 50 expands along the outer cortex 80 of thebone, providing secure fixation of the FAD to the outer cortex portion80 of the bone. The interference region and flange can be providedhaving one or more slots 60 therein to allow expansion of the wall whichcomprises the interference region and flange in response to a screwpassing through the interference region. The slots extend through theentire thickness of the sleeve. As a screw is inserted into the FAD, theslot in the sleeve portion of the FAD allows the sleeve portion of theFAD to expand thus pressing the walls of the sleeve into the bone on theinner walls of the drill hole.

The expansion of the flange portion of the sleeve can be enhanced byfilling a portion of the distal end of each inner surface of the sleevesuch the outer surface of the distal end of the screw pushes against thefilled inner surface at the distal end of the sleeve. As the screwpasses from the hollow portion of the sleeve into the filled distal-endportion of the sleeve it abuts the solid inner wall which causes furtherexpansion of the distal end and also prevents the flange from collapsingwhen pullout stress is applied. This approach further increases pulloutstrength of the FAD.

A second embodiment of a FAD 110, is shown in FIG. 2. The FAD 110 has asimilar structure as FAD 10. FAD 110 includes a collar 120, a core 130,an interference region 140, a flange portion 150 and a slot 160.Operation of FAD 110 is similar to the operation of FAD 10 describedabove. FAD 110 clips into place in a bone hole. Slot 160 allows for theends of the FAD to adequately clip into place.

Referring now to FIGS. 3A-B, another embodiment 310 of a FAD is shown.In this embodiment the interference region is provided having aplurality of ridges or teeth 330 on an outer surface thereof. The ridges330 help secure the FAD within the bone hole. FAD 310 further includeswings 370 in the interference region which expand in response to a screwpassing through the interference region and which secure the FAD withinthe bone hole. The outer walls of the FAD 310 can be ribbed, threaded orfretted to enhance the fixation of the device within the bone hole.Further the outer surface of the collar can also be ribbed, threaded orfretted to enhance the fixation of the device. As shown in to FIG. 3B,the interference region includes wings 375 in an end portion thereofwhich expand in response to a screw passing through the interferenceregion such that when the wings are deployed, the wings engage an outersurface of the bone and increase the pull force required to remove theFAD 310 from the bone hole.

Referring now to FIGS. 4A-B, an embodiment of another Fad 410 is shown.This embodiment uses a “clip” style body having an aperture 430 disposedmost of the way through. The aperture 430 includes a threaded region 470along an inner wall. The threaded region helps secure a screw in thebody to provide an expanding wedge type fit within the bone hole. Acollar region 420 is disposed at a first end of the body and is disposedon the surface of the bone at a first end of the hole to secure the bodyin a desired location within the hole. A second, opposite end of theinterference region has a second collar portion 450 coupled thereto. Thesecond collar portion is adapted to mate to the surface of the bone at asecond, opposite end of the hole. The second collar region helps securethe FAD 410 in the hole and increases pullout strength of the FAD.

FIG. 5 shows a FAD useful for smaller holes. FAD 510 is are providedfrom a single member which fills only a portion of a hole in a bone. FAD510 includes collar 520 and 550 on opposing ends thereof. The FAD 510may also have threads 570 provided therein. This FAD 510 function in asimilar manner as those described above with respect to FIGS. 4A-B.

Referring now to FIGS. 6A-B, a “split” FAD 610 is shown. This FAD 610 iscomprised of two complimentary pieces 611 and 612, each piecerepresenting approximately half of the FAD. Alternately, the Fad can becomprised as a single piece which splits into two pieces upon insertionof screw 670. Each piece includes a respective collar portion 620,interference region 640 and flange region 650. The FAD is inserted intothe bone hole, and upon insertion of a screw 670 the pieces 611 and 612are separated and provide interference fit of the screw within the bonehole. The operation of the FAD 610 in other respects is similar to thatof FIGS. 1A-C described above.

Referring now to FIGS. 7A-B, a telescoping FAD 710 is shown. This FAD710 includes a distal portion 730 and a proximal portion 740. The twoportions 730 and 740 are provided having geometries such that theportions can telescope (e.g. the distal portion can move into theproximal portion). Screw insertion pulls the distal portion 730 into theproximal portion 740 causing expansion of the proximal portion. Flaredout edges of the proximal portions provide the FAD having improvedfixation at the proximal cortex on the intramedullary side. A slot 760expands upon insertion of screw 770 and flange 750 provides for secureengagement of the FAD within the bone hole. As shown in FIG. 8A, priorto engagement of the FAD 710, a fracture line 790 of a bone isuncompressed. In FIG. 8B, after insertion and engagement of the FAD 710,the fracture line 790 is compressed.

Referring now to FIG. 8, an apparatus 810 for holding a FAD during a FADor screw insertion process includes a handle 820 and a body 830 coupledto the handle. The body 830 is adapted to hold a FAD while the FAD isinserted in a bone hole. The body holds the FAD in a manner which stillallows insertion of a screw into the FAD. In one embodiment, the body isprovided having a hole therein through which the screw can be insertedinto the FAD. The apparatus can also include a FAD anti-rotationstructure which minimizes FAD or even prevents FAD rotation which canoccur when a screw is inserted into the FAD.

The procedure for FAD installation will now be described. Once thesurgeon realizes that he/she has either sub-optimal fixation or asub-optimally positioned drill hole, the hole is over drilled utilizingan appropriately sized larger drill (i.e. 4.0 mm drill for a 3.5 mmcortical screw). The FAD length corresponding to the selected screwlength is then placed onto the FAD inserter and placed securely into thedrill hole. Now the screw is inserted into the FAD. As the screwadvances the walls of the FAD expand giving interference fixation to thebone along the inner walls of the drill hole. In addition, the expansionallows the FAD to hook over the inner side of the cortex with the flangeat the central portion of the interference region. The FAD expands evenfurther at the distal end and deploys the distal flange over the edge ofthe distal cortex, increasing the fixation to the bone. Once the screwis fully seated, secure fixation is once again established.

In one embodiment, the FAD can be used with a bone plate. In such anembodiment, the collar portion of the FAD is provided having a size andshape which allows the sleeve portion of the FAD to be inserted into ahole in a bone through a bone plate. Thus, when the FAD is used inconjunction with a bone plate, the sleeve portion of the FAD fitsthrough an opening in the bone plate and is inserted into a hole whichhas been drilled in a bone while the collar portion of the FAD fitsthrough the opening in the bone plate but does not fit within the holein the bone. The collar portion of the FAD can be provided having ashape which allows insertion of the FAD through the opening in the platebut which prevents rotation of the FAD during screw insertion. Forexample, in the case where the opening in the bone plate is providedhaving a round shape, the collar portion of the FAD can be providedhaving an oval shape. In this case, the edges of the collar would makeinterfering contact with the walls of the plate which define the hole tothereby prevent rotation of the FAD. This would not be accomplished witha round collar. Small fins beneath the collar also help to accomplishthis task.

Although, in the above examples the FAD collar portion is providedhaving an oval shape, it should be appreciated that any shape, includingbut not limited to rectangular, triangular, polygonal or even irregularshapes can be used. The particular shape with which to provide thecollar portion of the FAD depends upon a variety of factors includingbut not limited to the size and shape of the opening in the bone plate,the size of the FAD, the strength required to withstand forces appliedto the collar portion of the FAD and the materials from which the boneplate and FAD are manufactured.

Referring now to FIGS. 9A-9G in which like elements are provided havinglike referable designations throughout the several views, a first FAD901 includes a tubular body or sleeve portion 902. The sleeve 902 has acollar 904 disposed on a first end thereof. Collar 904 preferably has agenerally oval shape that prevents rotation of the device when insertedinto a bone plate or to allow a surface for a tool to use during theinsertion of the device 901 or during insertion of a screw into thedevice 1. The sleeve 902 is provided having an outside diameter D₁ (FIG.9D) selected such that the sleeve fits into a hole drilled in a bone.The collar 904 at the first or proximal end of the sleeve 902 preventsadvancement of the FAD 901 into the hole with screw insertion. Thesecond end of tube 902 has one or more flanges 908 coupled thereto. Inthe exemplary embodiment of FIGS. 9A-9G, device 901 is shown having fourflanges 908. Those of ordinary skill in the art will appreciate ofcourse that device 901 could include fewer or more than four flanges908. Surfaces 910 (FIG. 9B) of the flanges 908 are angled to allow theflanges to be placed in both an open position (FIG. 9B) and a closedposition (FIG. 9A).

Upon insertion of a screw into core 906 of the sleeve 902, flanges 908expand (as shown in FIG. 9B), providing secure fixation of the FAD 901to the bone. The angled sidewalls 910 of the flanges 908 also allow theFAD 901 to be removed from the hole in the bone if desired. The screw ispreferably withdrawn from the FAD 901 by an amount which allows theflanges 908 to collapse by an amount which allows the FAD 901 to beremoved. This can be accomplished by partially unscrewing the screw fromthe FAD by an amount which allows the flanges to close by an amountsufficient to allow the FAD to be withdrawn from the bone. This amountmay be a full collapse of the flanges back into the closed position. Or,it may be a partial collapse of the flanges to less than the fullyclosed position by an amount which still allows the FAD to be removed.Thus, in this case, the screw is not totally removed from the FAD. Insome cases, however, it may be desirable or necessary to fully removedthe screw from the FAD to allow the FAD to be removed.

Referring now in particular to FIG. 9D additional features of the FAD901 are shown. The FAD includes a thread 912 for receiving a screwtherein. Thread 912 is preferably located at the distal end of body 902and proximate flanges 908. In one embodiment, the thread 912 is locatedto account for a “run-in” region of a screw.

As shown in FIG. 9G, a first surface 912 a of thread 912 is spaced by apredetermined distance D₂ from a first surface 904 a of the collar 904and a second surface 912 b of thread 912 is spaced by a predetermineddistance D₃ from the first surface 904 a of the collar 904. In oneembodiment, for an overall device length of about 0.294 inches, thedistances D1 and D2 correspond to about 0.090 inches and about 0.137inches respectively, flange lengths L₂ (FIG. 9C) correspond to about 157inches and slot openings S₁ (FIG. 9C) are about 0.039 inches and S₂(FIG. 9C) about 0.080 inches. Other lengths, diameters and slot sizesmay, of course, also be used. The particular length and overall upper(i.e. collar) and lower (i.e. flange) diameters to be use in anyparticular application will be determined in accordance with a varietyof factors including but not limited to the length and diameter ofscrews being inserted. Likewise, the particular size of slot openings tobe used in any application will be determined in accordance with avariety of factors including but not limited to the length and overalldiameter of the FAD as well as the length and diameter of screws beinginserted into the FAD. Also, the FAD 901 is provided having a lowerflange diameter D₂ (FIG. 9F) in the range of about 0.254 inches and aflange having a length F₁ between flat section of about 0.165 inches anda radius R of about 0.0825 inches and a length L₃ of about 0.207 inches

In another embodiment, for an overall device length of about 0.304inches, the distances D₂ and D₃ correspond to about 0.104 inches andabout 0.147 inches respectively.

In still another embodiment, for an overall device length L of about0.508 inches, the distances D₁, D₂, D₃ and D₄ (FIG. 9F) correspond toabout 0.181 inches, 0.144 inches, 0.274 inches and about 0.312 inchesrespectively; and the distances L2 and L3 are about 0.234 and about0.300, respectively.

Also shown in FIG. 9G is a junction area 916 where a flange 908 joinsand emanates from body 902. Junction area 916 serves as a hinge or pivotpoint for the flanges 908. The junction area 916 is preferably sized toallow the flange 908 to be displaced from a closed position to an openposition, and also to allow the flange 908 to be returned to the closedposition from the open position. If this area is too thick, a relativelylarge amount of force will be required to cause the flange to open andthus it will be difficult to insert the screw. It will also be difficultto remove the FAD once the screw is removed. On the other hand, if thejunction area is too small, there is a likelihood of the junctionbreaking, resulting in the device becoming unusable. The junction area916 is preferably provided having a generally curved outer surface 917and a generally curved inner surface 918 to reduce an occurrence ofsharp bend points that could compromise the structure integrity of thejunction. One exemplary junction area 916 is shown in FIG. 9G.

The flanges 908 are designed to meet several criteria. While the numberof flanges 908 shown in the drawings is four, any number of flanges 908could be used depending up on the application requirements. The size ofthe flanges 908 are determined such that when the flanges 8 are in theclosed position (as shown in FIG. 9A) the flanges 908 can be insertedinto a hole which has been prepared in the bone while still providing asufficient interference fit within the hole after a screw is insertedwithin the device 901. The shape of the flanges 908 is also selected toallow sufficient interference fit when deployed (FIG. 9B), and furtherto allow the device 901 to be removed with minimal stress being placedon the bone.

An alternate embodiment of a FAD 1020 is shown in FIG. 10. In thisembodiment the FAD 1020 includes a body 1022, collar 1024, core 1026,flanges 1028 and junction points 1034 which may be similar to thosedescribed above in conjunction with FIGS. 9A-9G. FAD 20 has threads 32extending substantially the length of the opening 1026. Thus, when ascrew is inserted into FAD 1020, the screw remains in threadedengagement with the flanges 28 as they are deployed from a closedposition to an open position.

Another alternate embodiment is shown in FIG. 11. In this embodiment,the FAD 1140 has a similar body 1142, collar 1144, core 1146, flanges1148 and junction points 1152 as that of the FAD 901 described above inconjunction with FIGS. 9A-9G. The flanges 1148 in FAD 1140 have anengagement portion 1148 including a generally semi-circular shaped outerwall surface 1150. The outer wall surface 1150 provides for securefixation of the device within a bone or plate since the semi-circularshaped ends can fit over an outer surface of the bone or plate the FAD1140 is being affixed to.

Referring now to FIGS. 12A and 12B, a collar 1262 of FAD 1260 is shownwhich is preferably used with a type of bone plate known as acompression plate (CP) which may, for example, be provided as DynamicCompression Plate. A CP has one or more holes for receiving a screwwherein the inner surface of the screw hole has a sloped surface suchthat as a screw is inserted, the plate compresses the bone together.Collar 1262 of FAD 60 features a sloped collar surface 1264 about core1270 to match the sloped inner surface of a hole in the CP. The outeredge portion 1268 has a larger cross-sectional area than outer edgeportion 1266, thus providing a slope region for collar 1262.

Referring now to FIGS. 13A-13D, a fourth embodiment of a FAD 1370 isshown. FAD 1370 includes a tubular body or sleeve 1372. The sleeve 1372has a collar 1374 disposed on a first end thereof. Collar 1374preferably has a generally oval shape that prevents rotation of thedevice when inserted into a bone plate or to allow a surface for a toolto use during the insertion of the device or during insertion of a screwinto the device. A generally oval shoulder section 1384 is shownextending from the collar 1374. Shoulder 1384 has a tapered outer wallsurface 1384 a (FIG. 13D) and a tapered inner wall surface 1384 b. FAD1370 is preferably used with a bone plate, wherein the collar 1374extends through a hole in the bone plate while shoulder 1384 extendsinto and engages an inner surface of the hole in the bone plate. The FAD1370 is inserted into the bone plate hole and into the bone hole. When ascrew is inserted into FAD core 1378, the FAD 1370 is securely engagedwith the bone plate by way of shoulder 1384, while FAD 1370 itself issecured to the bone hole by flanges 1380.

A FAD may be provided having a bone in-growth treatment 1381 appliedthereto. The bone in-growth treatment 1381 could be a coating that isapplied to the FAD, such as hydroxyapatite or could be realized as atreatment which is performed on the FAD to result in a textured surfacewhich promotes bone in-growth to aid in securing the FAD to the bonestructure. The bone in-growth treatment 1381 could be applied to atleast a portion of one or more flanges 1382, at least a portion of thecollar 1376, at least a portion of the sleeve 1372 or a combinationthereof. The use of a FAD having a bone in-growth treatment 1381 appliedthereto is particularly useful in scenarios where the bone may not havea large amount of mass for a FAD to attach to or where the FAD will beused as part of a structure that may support a lot of movement orweight, for example in securing a replacement hip socket to a pelvicbone.

The sleeve 1372 is provided having an outside diameter selected suchthat the sleeve fits into a hole drilled in a bone. The collar at thefirst or proximal end of the sleeve prevents advancement of the FAD 1370into the hole with screw insertion. Upon insertion of a screw into core1378 of the sleeve 1372, flanges 1380 expand (as shown in FIG. 13B),providing secure fixation of the FAD 1370 to the bone. The angledsidewalls 1382 of the flanges 1380 are provided such that the FAD 1370may be removed from the hole in the bone if desired. Removal of thescrew from the FAD 1370 allows the flanges 1380 to be collapsed suchthat the FAD 1370 can be removed.

Referring now in particular to FIG. 13D additional features of the FAD1370 are shown. The FAD 1370 includes a thread 86 for receiving a screwtherein. Thread 1386 is preferably located at the distal end of body1372 and proximate flanges 80. The position of the thread 1386 from thecollar 1384 is selected to accommodate the run-in of the screw threadbeneath the screw head and then the thread 1386 on the inner wall ispreferably provided as short as possible to minimize the length of thetube portion. It could, in some applications, be desirable to lengthenthe tube portion (e.g. as shown in FIG. 11) so then the thread positionmay not be close at all to the flange. The “run-in” length assumes usewith current bone screws but conceivably a screw with a minimal, oressentially no run-in, could be used in conjunction with the FAD. Alsoshown in FIG. 13D is the junction area 1388 where a flange 1380 emanatesfrom body 1372.

This junction area 1388 serves as the hinge or pivot point for theflanges 1380. The junction area is preferably sized and located relativeto the flanges to allow the flanges to be displaced from a closedposition to an open position, and also to allow the flanges to bereturned to the closed position from the open position. Specifically,the thickness of the wall in the junction area should preferably beselected to allow the flanges 1380 to move from a closed position to anopen position and then back to a closed position again if necessary. Ifthe junction area is too thick, it will be difficult to insert the screwand to obtain the desired purchase within the bone and it will also bedifficult to remove the FAD once the screw is removed. On the otherhand, if the junction area is too small, there is a likelihood of thejunction breaking, resulting in the device becoming unusable. Thejunction area 1388 is preferably provided having a generally curvedouter surface and a generally curved inner surface to reduce anoccurrence of sharp bend points that could compromise the junction.

The flanges 1380 are designed to meet several criteria. While the numberof flanges shown in the drawings is four, any number of flanges could beused depending on the application requirements. The size of the flangesare determined such that when the flanges are in the closed position theflanges can be inserted into the drill hole while still providing asufficient interference fit within the hole of the bone when a screw isinserted within the device. The shape of the flanges is also selected toallow sufficient interference fit when deployed, and further to allowthe device to be removed with minimal stress being placed on the bone.

Referring now to FIG. 14A, another embodiment of a FAD 1490 is shown.The FAD in this embodiment is similar to FAD 1370 described above inconnection with FIGS. 13A-13D above and has some additional features.FAD 1490 includes a sleeve 1492, a core 1494, flanges 1496 and a collar1498, generally similar to the FADs described above in conjunction withFIGS. 9A-13D. Collar 1498 is provided with an external thread 100 whichis used to attach the FAD to a bone plate and to prevent the FAD fromrotating within the bone or bone plate when a screw is inserted into thecore 1494. Collar 1498 is also provided with a flat outer surfaceportion 14102. This flat outer surface portion 14102 provides a placefor an anti-rotation device to secure the FAD while a screw is removedfrom core 1494. Collar 1498 further includes a slot 14104 disposedacross an inner surface of the collar 1494. The slot 14104 accommodatesa flat blade of a screw driver. A screw driver can be used to rotate theFAD 1490 by way of slot 14104 to unlock the FAD from the bone plate,such that the FAD 1490 could then be removed.

Referring now to FIGS. 14B and 14C, a FAD 1490′ is shown. FAD 1490′ issimilar to Fad 1490 and includes a sleeve 1492, a core 1494, flanges1496 and a collar 1498′. Collar 1498′ is also provided with an externalthread 14100 which is used to attach the FAD to a bone plate and toprevent the FAD from rotating within the bone or bone plate when a screwis inserted into core 1494. Collar 1498 further includes a slot 14104disposed across an inner surface of the collar 1494. Collar 1498′ isprovided with multiple flat outer surface portions 14102. These multipleflat outer surface portions provide a place for an anti-rotation deviceto secure the FAD while a screw is removed from core 1494.

Referring now to FIG. 14D, a FAD 1490″ is shown. FAD 1490″ is similar toFad 1490 and includes a sleeve 1492, a core 1494, flanges 1496 and acollar 1498. Collar 1498 is provided with an external thread 14100 whichis used to attach the FAD to a bone plate and to prevent the FAD fromrotating within the bone or bone plate when a screw is inserted intocore 1494. Collar 1498 further includes a slot 104 disposed across aninner surface of the collar 1494. Collar 1498 is provided with multipleflat outer surface portions 14102. These multiple flat outer surfaceportions provide a place for an anti-rotation device to secure the FADwhile a screw is removed from core 1494. In this embodiment the collarincludes a tapered outer surface portion 14106. The tapered outersurface portion 14106 is used for mating with a bone plate having a holewith a corresponding tapered or counter-sunk inner surface.

The FADs described herein are preferably comprised of stainless steelalthough other materials such as titanium or a bio-absorbable materialhaving acceptable mechanical properties could be used. Also, plasticssuch a polymethylmethacrylate (PMMA) or other biocompatible plastics canalso be used. Although in the examples provided herein the FAD collarportion is sometimes provided having a circular or oval shape, it shouldbe appreciated that any shape, including but not limited to rectangular,triangular, polygonal or even irregular shapes can be used. Theparticular shape with which to provide the collar portion of the FADdepends upon a variety of factors including but not limited to the sizeand shape of the opening in the bone plate, the size of the FAD, thestrength required to withstand forces applied to the collar portion ofthe FAD and the materials from which the bone plate and FAD aremanufactured.

The FAD can be used with a bone plate. In such an embodiment, the collarportion of the FAD is provided having a size and shape that allows thesleeve portion of the FAD to be inserted into a hole in a bone through abone plate. Thus, when the FAD is used in conjunction with a bone plate,the sleeve portion of the FAD fits through an opening in the bone plateand is inserted into a hole which has been drilled in a bone while thecollar portion of the FAD fits through the opening in the bone plate butdoes not fit within the hole in the bone. The collar portion of the FADcan be provided having a shape which allows insertion of the FAD throughthe opening in the plate but which prevents rotation of the FAD duringscrew insertion. For example, in the case where the opening in the boneplate is provided having an oval shape, the collar portion of the FADcan also be provided having an oval shape. In this case, the edges ofthe collar would make interfering contact with the walls of the platethat define the hole to thereby prevent rotation of the FAD. This wouldnot be accomplished with a round collar.

Referring now to FIG. 15, once it is required that a FAD is required(e.g. because a surgical screw fails to provided a desired or adequatepurchase (or fastening strength), then one possible procedure for FADinstallation includes aligning a bone plate over a bone, using existingholes in the bone plate as a guide to drill one or more holes into (andpartially or fully) through the bone. With the bone plate aligned overthe holes, the FAD is disposed through the hole in the bone plate andinto the hole which was drilled in the bone. A screw 15118 is theninserted through the hole 15116 in the bone plate 14114 and into the FAD901. As the screw advances, the flanges of the FAD 901 expand givinginterference fixation to the bone along the inner walls of the drillhole 15112. Once the screw 15118 is fully seated, secure fixation of thebone plate 15114 to the bone 15110 is established.

Another possible procedure for FAD installation includes is described.Once a surgeon or other medical practitioner has determined that a FADis required, a hole 15112 is drilled into bone 15110 utilizing anappropriately sized drill for the FAD 901 being used. The FAD 901 isthen placed into the drill hole 15112. The bone plate 15114 is thenpositioned on bone 15110 such that the hole 15116 in bone plate 15114 isaligned with the hole in FAD 901. Once aligned, a screw 15118 isinserted through the hole 15116 in bone plate 15114 and into the FAD901. As the screw advances, the flanges of the FAD 901 expand givinginterference fixation to the bone along the inner walls of the drillhole 15112. Once the screw 15118 is fully seated, secure fixation of thebone plate 15114 to the bone 15110 is established.

Referring now to FIG. 16, an alternate procedure for FAD installation isshown. Once the surgeon has determined that a FAD is required, a hole16122 is drilled into bone 16120 utilizing an appropriately sized drillfor the FAD 901 being used. The bone plate 16124 is then positioned onbone 16120 such that the hole 16126 in bone plate 16124 is aligned withthe hole 16122 in the bone 16120. The FAD 901 is then placed into andextending through the hole 16126 of bone plate 16124 and into the drillhole 16122 of bone 16120. A screw 16128 is inserted into the FAD 901. Asthe screw advances, the flanges of the FAD 901 expand givinginterference fixation to the bone along the inner walls of the drillhole 16122. Once the screw 16128 is fully seated, secure fixation of thebone plate 16124 to the bone 16120 is established.

Referring now to FIG. 17A an embodiment of a FAD 17130 used with alocking plate 17132 is shown. Locking plate 17132 is similar to boneplate 17124 shown in FIG. 16, except that the hole 17136 in lockingplate 17132 has threaded, tapered side walls 17134. The threaded taperedside walls 17134 mate with a threaded external surface 17138 of FAD17130. In this embodiment the FAD 17130 is inserted into the hole 17136and rotated a predetermined amount to securely mate the FAD 17130 withinthe locking plate 17132. As shown, a top surface of the inserted FAD17130 is generally coplanar with the top surface of the locking plate17132.

Referring now to FIG. 17B an embodiment of a FAD 17142 which is alsoused with a locking plate 17132 is shown. The threaded tapered sidewalls 17134 of hole 17136 in locking plate 17132 mate with a threadedexternal surface 17138 of FAD 17142. In this embodiment the FAD 17142 isinserted into the hole 17136 and rotated a predetermined amount tosecurely mate the FAD 17142 within the locking plate 17132. A topsurface of the inserted FAD 17142 is recessed within hole 17136. Thisallows for a screw (not shown) inserted into FAD 17142 to have it's topsurface be generally co-planar with the top surface of locking plate17132 when the screw is completely inserted into the FAD 17142.

Referring now to FIG. 18, a device 17150 is shown which comprises atleast one FAD portion and a bone plate portion integrated together as asingle unitary device. The device 17150 includes a bone plate portion17152 and one or more FAD portions 17154. A FAD portion 17154 includes asleeve 17156, flanges 17158, and a core 17160. This device 17150replaces a combination of a bone plate and separate FAD devices with asingle unitary device providing similar functionality.

Referring now to FIGS. 19A-19H in which like elements are providedhaving like reference designations throughout the several views, anotherembodiment of a FAD 19190 is shown. The FAD in this embodiment issimilar to FAD 1490 described above in conjunction with FIGS. 14A-14Dbut has some additional features including a release cam lock mechanismas will be described below. The FAD 19190 includes a sleeve 19192, acore 19194, flanges 19196 and a collar 19198, generally similar to FADsdescribed above and a release cam lock mechanism 19200.

The Collar 19198 is provided having a pair of openings 19202. Theopenings 19202 are provided having a size and shape selected to accept aremoval tool. In this particular example, the openings 19202 areprovided having a rectangular-slot shape which accepts a flat tip of aremoval tool. This aids in placing the device 19190 in proper alignmentwithin a bone plate hole during insertion and removal of the device19190.

During initial insertion of the device 19190 in a bone plate having anoval hole, the holes 19202 are aligned with the major (i.e. the longer)axis of the oval hole of the plate. This alignment insures that thedevice 19190 will seat properly in the bone plate during insertion as itis aligned with the oval shape of the locking mechanism 19200 beneaththe collar 19198. With screw insertion and seating, the device 19190rotates into a locked position on the plate and the holes 19202 show theorientation of the device 19190 to have rotated in the direction of theminor (i.e. the shorter) axis of the oval hole in the bone plate.

If the device 19190 and a screw have been inserted and it is desired toremove them, during the removal process the screw is withdrawn (eitherpartially of fully) and once the screw is withdrawn from the device, theremoval tool can be used to re-orient the openings 19202 of the device19190 so they are once again aligned with the major axis of the ovalhole in the bone plate. This insures that the device 19190 is no longerlocked onto the plate and can be safely removed.

Flat surfaces 19204 on the collar 19198 are present to allow use of ananti-rotation tool if needed during supplement insertion and removal.The anti-rotation tool is a device used to prevent the device 19190 fromrotating during the screw insertion and removal processes. The flatsurfaces also provide a visual cue to properly align the device 190during insertion and removal of the device 19190. Similar to the slot19202 in the collar 19198, the flat collar surfaces 19204 are alignedwith the major axis of an oval hole in a bone plate during initialinsertion and just prior to removal. This alignment insures that thedevice 19190 is no longer locked onto the plate as occurs when thesupplement rotates slightly with screw insertion and seating as willbecome apparent from the description of FIG. 20 hereinbelow.

In this particular embodiment, the locking mechanism 19200 includes thecollar 19198, one or more expansion or cam regions 19206 beneath thecollar 19198 and a tab 19208 which is below the collar 19198 andexpansion regions 19206. In the embodiment shown in FIGS. 19A-19H, twocam regions 19206 are shown (best seen in FIG. 19E). The cam regions19206 are provided in a cam arrangement with an offset from the devicecenterline by approximately 0.002 inches.

In one exemplary embodiment, the length L₁ (FIG. 19E) is in the range ofabout 0.188 to about 0.190 inches and the about and the length L₂ (FIG.19E) is in the range of about 0.166 inches to about 0.168 inches. Alsothe lengths L₃ (FIG. 19D) and L₄ (FIG. 19D) of the tab region are in therange of about 0.190 to about 0.200 inches and in the range of about0.164 to about 0.166 inches, respectively.

The expansion areas can be provided by having a portion of the sleeve19192 made to have an oval shape or by having a portion of the sleeve19192 made to have a cam-type arrangement as described above.

Also, as can be seen by comparing FIGS. 19D and 19E, the expansion areas19206 are slightly misaligned with the tab 19208. This slightmisalignment allows the tab 19208 to move underneath the plate (e.g.plate 20216 in FIG. 20) prior to the cam regions 19206 contacting asurface of the hole in the compression plate. This prevents furtherrotation of the FAD in the hole of the compression plate. In oneembodiment, for a FAD having an overall length of about 0.3 inches (i.e.length from a top surface of the collar to a bottom surface of aflange), the thickness T₁ of the expansion area 20206 is in the range ofabout 0.032 inches and the thickness T₂ of the tab 20206 is in the rangeof about 0.009 inches. Other thickness and axis lengths for theexpansion and tab regions may also be used depending upon the needs ofany particular application. In one embodiment the major axes of theexpansion area and tab are offset by about three and on-half degreesalthough offsets in the range of about one to about thirty degrees maybe used depending upon a variety of factors including the size of theFAD (including the lengths of the major and minor axes of both theexpansion region and tabs) as well as the lengths of the major and minoraxes of the hole in the compression plate (or other structure) in whichthe FAD will be disposed.

As will be described below in conjunction with FIG. 20, when the device19190 is inserted the device 19190 rotates with screw insertion and thetab 19208 feeds underneath the plate (e.g. plate 20216 in FIG. 20). Thisprevents the device 19190 from moving up and down within the plate holeand insures proper contact of the plate and device 19190. The expansionarea 19206 is positioned with respect to the tab 20208 such that uponrotation of the device, the expansion area 19206 contacts an inner wallor surface (e.g. wall 20214 a in FIG. 20) of the plate hole just afterthe tab 19206 feeds under the plate (e.g. plate 20216 in FIG. 20).

Because the length of the major axis of the expansion area 19206 islonger than the length of the minor axis of the oval hole in the plate,further rotation of the device 19190 is prevented. However, the longaxes for both the oval expansion and the tabs are short enough relativeto the long axis of the oval plate hole to allow easy seating of thesupplement during insertion of the device (i.e. both the tab and theexpansion have to fit and the length of the major axis for the tab isslightly greater that the length of the major axis for the expansion).

It should be appreciated that the device 19190 may also be providedhaving features above such as flat (rather than beveled) internal and/orexternal collar surfaces. Also, the FAD 19190 may be provided having abone in-growth treatment such as that described above. As mentionedabove, the bone in-growth treatment could be a coating that is appliedto the FAD, or could be realized as a treatment which is performed onthe FAD to result in a textured surface which promotes bone in-growth toaid in securing the FAD to the bone structure. The bone in-growthtreatment could be applied to at least a portion of one or more flanges19196 (either inner or outer flange surfaces), at least a portion of thecollar 19198, at least a portion of the sleeve 19192 or a combinationthereof. The use of a FAD having a bone in-growth treatment appliedthereto is particularly useful in scenarios where the bone may not havea large amount of mass for a FAD to attach to or where the FAD will beused as part of a structure that may support a lot of movement orweight, for example in securing a replacement hip socket to a pelvicbone.

In one exemplary embodiment, the FAD 19190 has an overall length L (FIG.19C) of about 0.340 inches, a lower diameter D₁ (FIG. 191) in the rangeof about 0.254 inches, a flange diameter D₂ (FIG. 19C) of about 0.250in. and slot openings S₁ (FIG. 19H) in the range of about 0.039 inchesand S₂ (FIG. 19H) in the range of about 0.090 inches. Other lengths,diameters and slot sizes may, of course, also be used. The particularlength and overall upper (i.e. collar) and lower (i.e. flange) diametersto be use in any particular application will be determined in accordancewith a variety of factors including but not limited to the length anddiameter of screws being inserted. Likewise, the particular size of slotopenings to be used in any application will be determined in accordancewith a variety of factors including but not limited to the length andoverall diameter of the FAD as well as the length and diameter of screwsbeing inserted into the FAD.

Referring now to FIG. 20, in which like elements of FIGS. 19A-19G areprovided having like reference designations, a portion of a bone 20206is shown to include an upper bone region 20210 a, a lower bone region20210 b and a space region 20212 between the upper and lower boneregions 20210 a, 20210 b. A hole 20214 is provided through both theupper and lower bone regions 20210 a, 20210 b. Thus, the hole 20214 maybe referred to as a “through hole” meaning that the hole provides a paththrough the entire bone 20206.

It should be appreciated, of course, that the hole 20214 need only passthrough one bone portion (e.g. either bone portion 20210 a or 20210 b).Those of ordinary skill in the art will appreciate how to determinewhether the hole 20214 should be provided to pass through only one ofthe bone regions 20210 a, 20210 b or whether it should pass through allregions of a bone (e.g. through both regions 20210 a, 20210 b of bone20206.

A plate 20216 (e.g. a bone or compression plate) having an hole thereinis disposed over the bone portion 20210 a with the plate hole alignedwith the hole 20214 in the bone portion 20210 a. Once the plate hole andbone hole 214 are aligned, the device 19190 is disposed in the hole 214.The device 19190 can then be turned such that the collar 19198 engages afirst surface of the plate 20216 and the tab 19208 engages a secondsurface of the plate.

In this particular embodiment, the hole 20214 in the plate 20216 isprovided having an oval shape and the major axis of the expansion area19206 (most clearly seen in FIG. 19E) of the device 19190 is longer thanthe minor axis of the oval hole in the plate 20216. By making the majoraxis of the expansion area 19206 of the device 19190 longer than theminor axis of the oval hole in the plate and by providing the expansionarea 19206 in a predetermined spatial relationship with respect to thetabs 19208, once the tabs 19208 engage the surface of the plate 20216,the expansion area 19206 prevents further rotation of the device 19190in the hole 20214.

A screw 20217 having a head portion 20218 and a body portion 20220 isdisposed in the device 19190. Insertion of the screw in the device 19190causes the flanges 19196 to open and secure the device 19190 in the holeand in particular in the space region 20212 of the bone 20206. Thedevice 19190 also includes the thread region 19222 which engages threads20224 provided in the screw body 20220. The screw threads 20224 engagethe thread 19222 which, in combination with the opened flanges 19196,allows the screw 20216 to be securely coupled to the bone 20206.

A space 20230 may exist between a bottom surface of the plate and asurface of the bone 20210 b, however, this space 20230 has substantiallyno impact on the ability of FAD 19190, plate 20216 or screw 20220 toserve their respective intended functions.

Having described preferred embodiments of the invention it will nowbecome apparent to those of ordinary skill in the art that otherembodiments incorporating these concepts may be used. Accordingly, it issubmitted that the invention should not be limited to the describedembodiments but rather should be limited only by the spirit and scope ofthe appended claims. All publications and references cited herein areexpressly incorporated herein by reference in their entirety.

1-44. (canceled)
 45. A fixation augmentation device (FAD) comprising: agenerally tubular body having a first end and a second end, said bodyhaving an opening adapted to receive a screw therein; a collar attachedto the first end of said body, said collar having a non-circular shapeand having an opening which is aligned with the opening in said body;and at least one flange disposed at the second end of said body, whereinsaid at least one flange is extendable from said body in response to ascrew being inserted into the hole of said body.
 46. The fixationaugmentation device of claim 45 wherein an outer wall surface of saidcollar is provided having an oval shape and said FAD is provided havinga plurality of flanges, each of said plurality of flanges coupled to thesecond end of said body and extendable from said body in response to ascrew being inserted into the hole of said body.
 47. The fixationaugmentation device of claim 45 wherein said collar has a non-uniformwidth.
 48. The fixation augmentation device of claim 45 wherein an outerwall of said collar has a generally tapered surface.
 49. The fixationaugmentation device of claim 45 wherein an inner wall of said collar hasa generally tapered surface.
 50. The fixation augmentation device ofclaim 45 wherein an outer wall of said flange has a generally flatsurface.
 51. The fixation augmentation device of claim 45 wherein anouter wall of said flange has a generally semi-circular shaped surface.52. The fixation augmentation device of claim 45 wherein an internalsurface of said body which defines the opening adapted to receive ascrew is provided having a single thread projecting therefrom, saidsingle thread adapted to engage the screw.
 53. The fixation augmentationdevice of claim 45 an internal surface of said body which defines theopening adapted to receive a screw is provided having an internalthreaded portion extending approximately the length of said body, saidthreaded portion adapted to engage the screw.
 54. The fixationaugmentation device of claim 45 further comprising a bone plate, saidbone plate having a bone plate hole disposed therethrough, said boneplate hole having a predetermined size selected to receive said tubularbody therein and such that said collar does not fit through the boneplate hole.
 55. The fixation augmentation device of claim 45 furthercomprising a locking plate, said locking plate having a hole providedtherein with the hole having a predetermined size and tapered threadedsidewall selected to receive said body therein.
 56. The fixationaugmentation device of claim 55 wherein said body includes an externalthreaded surface, said external threaded surface mating with saidthreaded sidewall of the locking plate hole and wherein said body isinserted into the locking plate hole such that a top surface of saidbody is generally aligned with a top surface of said locking plate. 57.The fixation augmentation device of claim 13 wherein said body includesan external threaded surface, said external threaded surface mating withsaid threaded sidewall of said hole and wherein said body is insertedinto said hole such that a top surface of said body is recessed withinsaid locking plate.
 58. The fixation augmentation device of claim 45further comprising wherein said collar is provided having a release-cammechanism.
 59. A fixation augmentation device (FAD) comprising: agenerally tubular body having a first end and a second end, said bodyincluding an interference region located between said first end and saidsecond end, said body insertable into a hole, said body adapted toreceive a screw therein; and a collar coaxially aligned and attached tothe first end of said body.
 60. The FAD of claim 60 further comprising aflange disposed at the second end of said body.
 61. The FAD of claim 61further comprising a slot extending from the second end of said body andalong a portion of said body, said slot extending completely through asidewall of said body.
 62. The FAD of claim 61 wherein said body has agenerally tapered shape.
 63. A fixation augmentation device (FAD)comprising: a first generally tubular body piece having a first end anda second end, said first body piece body including an interferenceregion located between said first end and said second end, said firstbody piece insertable into a hole, said first body piece adapted toreceive a screw therein; a second generally tubular body piece having afirst end and a second end, said second body piece insertable into ahole, said second body piece adapted to receive a screw therein, thefirst end of said second body receivable by said second end of saidfirst body piece when a screw is inserted in said first body piece andsaid second body piece; a collar coaxially aligned and attached to thefirst end of said first body piece; and a flange disposed at the secondend of said second body piece.